The effects of oxidation–reduction treatment on the structure and activity of cobalt-based catalysts

• Oxidation–reduction (OR) cycles improved the reducibility of a Ru-Co/Al2O3.
• The OR treatment promoted the formation of Ru-Co bimetallic structure.
• A 70% increase in CO conversion observed for an ROR-treated Ru-Co/Al2O3 catalyst.

This study reports the effects of oxidative-reductive (OR) treatment on 10 wt% Co/Al2O3 and 0.25 wt% Ru-10 wt% Co/Al2O3 catalysts. Temperature-programmed analysis revealed that the cobalt in both catalysts became more reducible with increase number of OR treatment. A reduction–oxidation–reduction treatment increased Co surface area and dispersion of the Ru-Co/Al2O3 catalyst from 7.6 to 10.1 m2/g and from 14.9% to 17.3%, respectively. The treatment also increased the CO conversion from 21% to 36% and accompanied a small increase in CH4 selectivity in Fischer–Tropsch synthesis experiments. However, the effect of OR treatment on the Co/Al2O3 catalysts was insignificant.

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